Outdoor tool and eddy current controlled lubrication system

Abstract

External tools and eddy current-controlled lubrication systems are described. A lubrication assembly may include a motor assembly, a drive plate, a driven rotor, a cam plate, and a positive displacement pump. The drive plate may be mechanically coupled to the motor assembly to rotate with it. The driven rotor may be spaced apart from the drive plate. The driven rotor may include a support substrate and one or more magnetic elements fixed to the support substrate to rotate with it. The one or more magnetic elements may be magnetically engaged with the drive plate to generate an eddy current. The cam plate may be attached to the support substrate to rotate with it.The positive displacement pump can be mechanically connected to the cam plate to drive the pumping of a lubricant fluid based on the rotation of the cam plate.

Description

Cross-reference to related registrations

[0001] The present application claims priority over US application number 63 / 723,647, filed on November 22, 2025, the disclosure of which is incorporated herein by reference in its entirety. Area

[0002] The present disclosure relates generally to lubrication systems for outdoor power tools, such as chainsaws, pole saws and the like. background

[0003] Garden tools such as pole saws and hand chainsaws are used for outdoor tasks like cutting branches and other vegetation. Pole saws and chainsaws cut material using chains with cutting teeth. The chain is typically mounted on a guide bar within a guide bar. The chain moves relative to the guide bar, driving the cutting teeth along the material being cut.

[0004] The frictional resistance between the chain and the guide bar reduces the saw's efficiency. This means that the additional resistance between the chain and the guide bar results in reduced energy capacity and fewer cuts that can be made between recharging or refueling. To address this issue, lubrication can be applied between the chain and the guide bar. However, excessive lubrication can attract dirt, interfere with the tool's electronic components, degrade the user experience, or even cause dripping. Many existing systems require complex gears and systems to deliver lubricant to the tool.For example, a worm gear can be used to transfer mechanical energy directly from a primary motor to a lubricant pump (such as a centrifugal pump or another pump that uses the kinetic energy of the lubricant to generate pressure energy for pumping). Such systems can be expensive, inefficient, and difficult to install, or they can take up a lot of space in the tool. Some systems even pose a risk of lubricant leakage, especially if the tool is not in use for extended periods.

[0005] Accordingly, improved lubrication systems for outdoor tools are desirable in engineering. In particular, outdoor tools or lubrication systems that provide sufficient lubrication while also being relatively robust, energy-efficient, or compact would be advantageous. Overview

[0006] Aspects and advantages of the present disclosure are partly set forth in the following description, or may be evident from the description, or can be learned through the practical application of the technique.

[0007] According to one embodiment, a lubrication system for a power tool is described. The lubrication system can comprise a motor assembly, a drive plate, a driven rotor, a cam plate, and a positive displacement pump. The drive plate can be mechanically coupled to the motor assembly to rotate with it. The driven rotor can be spaced apart from the drive plate. The driven rotor can comprise a support substrate and one or more magnetic elements fixed to the support substrate to rotate with it. The one or more magnetic elements can be magnetically engaged with the drive plate to generate an eddy current with it. The cam plate can be attached to the support substrate to rotate with it. The positive displacement pump can be mechanically connected to the cam plate to drive the pumping of a lubricating fluid based on the rotation of the cam plate.

[0008] According to a further embodiment, a tool is specified. The tool comprises a motor assembly, a tool unit, and a lubrication system. The tool unit can be driven by the motor assembly. The tool unit can include a guide bar and a chain that encloses a section of the guide bar. The lubrication system supplies the chain with lubricant. The lubrication system can include a drive plate, a driven rotor, a cam plate, and a positive displacement pump. The drive plate can be mechanically coupled to the motor assembly to rotate with it. The driven rotor can be spaced apart from the drive plate. The driven rotor can include a support substrate and one or more magnetic elements fixed to the support substrate to rotate with it.One or more magnetic elements can magnetically engage with the drive plate to generate an eddy current. The cam plate can be attached to the carrier substrate to rotate with it. The positive displacement pump can be mechanically connected to the cam plate to drive the pumping of a lubricating fluid to the chain based on the rotation of the cam plate.

[0009] These and other features, aspects, and advantages of the present disclosure will be better understood with reference to the following description and the accompanying claims. The accompanying drawings, which are included in and form part of this description, illustrate embodiments of the technology and, together with the description, serve to explain the principles of the technology. Brief description of the drawings

[0010] A complete and meaningful disclosure of the present application, which includes the best way of manufacturing and using the systems and processes presented, and which is addressed to a person skilled in the art in this field, is set out in the description which refers to the accompanying drawings in which: Fig. 1 a perspective view of an outdoor tool according to embodiments of the present disclosure; Fig. 2 a perspective view of a lubrication assembly according to embodiments of the present disclosure; Fig. 3 a perspective bottom view of a section of the exemplary lubrication assembly from Fig. 2 is; Fig. 4 a first perspective view of a pump bracket of the exemplary lubrication assembly from Fig. 2 is; Fig. 5 a second perspective view of a pump bracket of the exemplary lubrication assembly from Fig. 2 is; Fig. 6 a sectional view of a section of the exemplary lubrication assembly made of Fig. 2, along the intersection line 6-6 is and Fig. Figure 7 represents a schematic representation of the operation of a lubrication system according to embodiments of the present disclosure. Detailed description

[0011] Reference will now be made in detail to embodiments of the present disclosure, one or more examples of which are shown in the drawings. The word "exemplary" is used here to mean "serving as an example, case, or illustration." Each embodiment described here as exemplary is not necessarily to be understood as preferred or advantageous over other embodiments. Moreover, each example is given for clarification and not to limit the technology. Indeed, it will be obvious to the person skilled in the art that modifications and variations can be made in the present technology without departing from the scope or concept of the claimed technology. For example, features shown or described as part of one embodiment can be combined with another embodiment to obtain yet another embodiment.The present disclosure therefore covers all modifications and variations that fall within the scope of the appended claims and their equivalents. In the detailed description, numerical and letter designations are used to refer to features in the drawings. Identical or similar designations in the drawings and the description have been used to refer to identical or similar parts of the disclosure.

[0012] The terms "first," "second," and "third" may be used interchangeably to distinguish one component from another and are not intended to indicate the location or significance of any individual component. The singular forms "a," "an," and "the" encompass the multitude unless the context clearly indicates otherwise. The terms "coupled," "fixed," "attached to," and the like refer to both direct coupling, fixing, or attaching and indirect coupling, fixing, or attaching via one or more intermediate components or features, unless otherwise specified herein. The terms "includes," "comprehensive," "includes," "has," or other variations thereof, as used herein, are intended to include non-exclusive elements.For example, a process, procedure, object, or device that includes a list of characteristics is not necessarily limited to those characteristics but may also include other characteristics not expressly listed or inherent in such a process, procedure, object, or device. Unless expressly stated otherwise, "or" refers to an inclusive or and not an exclusive or. For example, condition A or B is satisfied if any of the following conditions is met: A is true (or present) and B is not true (or present), A is not true (or present) and B is true (or present), and both A and B are true (or present).

[0013] Terms of approximation such as "about," "generally," "approximately," or "essentially" include values ​​that are within ten percent above or below the stated value. When used in conjunction with an angle or direction, these terms include values ​​within ten degrees greater or less than the stated angle or direction. For example, "essentially vertical" includes directions within ten degrees of the vertical in any direction, such as clockwise or counterclockwise.

[0014] Advantages, other benefits, and problem solutions are described below with regard to specific embodiments. However, the benefits, advantages, problem solutions, and features that may lead to a benefit, advantage, or solution occurring or becoming more pronounced are not to be understood as significant, necessary, or essential features of one or all claims.

[0015] In general, the tools described here can utilize lubrication systems that do not require a direct mechanical connection between a motor and the pump. For example, the lubrication system may include an arrangement or system for inducing one or more eddy currents in response to the rotation of the motor. The eddy currents can drive the rotation of a driven plate, which in turn can drive the pump to pump a lubricant. Additionally or alternatively, the pump may include or be provided as a positive displacement pump. In particular, the tools or lubrication systems described here may be relatively robust (for example, compared to lubrication systems or assemblies in existing outdoor tools), energy-efficient, or compact. In some cases, air entrapment within the pump may be prevented.In an additional or alternative case, the flow rate (e.g., the volumetric flow rate) of the lubricant can be monitored or determined without additional wetted components in the lubrication system, which in turn can reduce the size, complexity, or risk of leaks.

[0016] Referring to the drawings, shows Fig. 1 A perspective view of a tool 100 according to exemplary embodiments of the present disclosure. In particular, the tool shown in Fig. The tool 100 shown is a chainsaw. The tool 100 has a lubrication system 102, which is arranged in a housing 104 of the tool 100. The tool 100 may also include a guide bar assembly 106, which accommodates a chain 126, for example, which is guided around the guide bar 116. As described in more detail below, the tool 100 may also include a motor assembly 110 and a lubrication system 102 (for example, within the housing 104), which is at least partially driven by the motor assembly 110. In the assembled state, one or more hoses or lines connected to the lubrication system 102 can generally convey or supply liquid lubricant (for example, lubricating oil) from the lubrication system 102 to the guide bar assembly 106 (as is understood, for example).

[0017] The tool 100 can include a variety of features and configurations to facilitate handling and operation by a user. For example, the housing 104 can include a first handle 136 (e.g., a top handle) connected between a battery receptacle or battery compartment 114 and a front section of the housing 104. Thus, the first handle 136 extends in one direction along the longitudinal axis LA of the guide blade 116. Furthermore, the housing 104 includes a second handle 138 (e.g., an elongated, curved rod) connected between the first handle 136 and a side wall of the battery receptacle 114.

[0018] A user interface, for example a trigger 118, can be located at a point where an operator can control the operation of the tool 100, such as at the first handle 136. The trigger 118 can control the motor assembly 110 of the tool 100 to drive the chain 126 along the guide bar 116. As a non-limiting example, the motor assembly 110 can include a motor with an output or input shaft. The input shaft can be connected to the chain 126, for example via a gearbox with a drive gear, to move the chain 126 along the guide bar 116. For example, the drive gear can be rotatably coupled to the gearbox, and the chain 126 can be operatively connected to the drive gear (for example, the chain 126 can circumscribe a section of the drive gear) so that the drive gear can drive the chain 126 around the guide bar 116.When the trigger 118 of the motor 110 is activated, i.e., pressed, the speed of the motor assembly 110 can increase. Conversely, the motor assembly 110 can stop when the trigger 118 of the motor 110 is deactivated, i.e., not pressed.

[0019] The motor assembly 110 can include any energy source or be designed to move the chain 126 directly or indirectly around the guide bar 116, such as a system motor 120, which is an electric motor ( Fig. 2) or is provided by an internal combustion engine. Optionally, the engine assembly 110 can be a variable-speed engine, whereby a relatively activated position of the trigger 118 can influence the speed of the variable-speed engine. That is, the operator can control the speed of the chain 126 along the guide bar 116 based on how far the trigger 118 is depressed. A secondary user interface, for example, a power switch (not shown), can be used to control another aspect of the tool 100. The power switch can, for example, include a toggle switch that can be moved between the ON and OFF positions. The tool 100 may not operate when the power switch is in the OFF position.

[0020] In Fig. 2, Fig. 3, Fig. 4, Fig. 5 to Fig. Figure 6 shows various views to illustrate a lubrication system 102 and aspects thereof according to exemplary embodiments. In general, a system motor 120 (for example, a motor assembly 110) is attached to one or more sections of the lubrication system 102. In particular, the system motor 120 can be mechanically coupled to or fixed to a drive plate 144 to rotate it. As described in more detail below, the drive plate 144 can be indirectly coupled or associated with one or more intermediate components to control the flow of lubricant from a provided oil tank or lubricant reservoir 130 (for example, attached to or enclosed in the housing 104). Fig. 1) to the chain 126 or the guide sword 116 ( Fig. 1) to drive or move.

[0021] In some embodiments, the system motor 120 comprises a drive shaft 142 extending along an axial direction A, which defines an axis of rotation for the motor 120. The drive plate 144 can be fixed to the drive shaft 142 and thus rotate simultaneously or synchronously with the drive shaft 142 about the axial direction A. Therefore, the drive shaft 142 and the drive plate 144 can be coaxial. As shown, the drive plate 144 can comprise, or be provided as, a magnetically permeable or conductive disk extending radially from the drive shaft 142 (or generally in the axial direction A). In other words, a disk made of a magnetically permeable or conductive metal (for example, non-ferrous metal) can be included in, or provided as, the drive plate 144.Optionally, a circumferential recess 146 can be defined in the conductive disk, for example on an upper surface 150 of the conductive disk or on a surface facing the motor.

[0022] In optional embodiments, a motor fan 148 is rotatably coupled to or fixed with the motor assembly 110 and the drive plate 144 in order to rotate with them. For example, the motor fan 148, which comprises one or more fan or impeller blades, can be fixed to the drive shaft 142 (for example, between a base of the system motor 120 and the drive plate 144 relative to the axial direction A). In the illustrated embodiments, the motor fan 148 is mounted on the conductive disk. In particular, the motor fan 148 is provided on the upper surface 150 of the conductive disk, or the surface facing the motor. In some such embodiments, the motor fan 148 is also located within the circumferential recess 146.

[0023] In addition to the drive plate 144, the lubrication system 102 also comprises a driven rotor 152. In particular, the driven rotor 152 can be spaced apart from the drive plate 144 so that neither section is in direct contact with the other. As shown in the illustrated embodiments, the driven rotor 152 can be axially spaced from the drive plate 144. Although the drive plate 144 can influence or induce the rotation of the driven rotor 152 (as described in detail below), the driven rotor 152 can be mechanically or rotatably decoupled from the drive plate 144 or the drive shaft 142. However, in optional embodiments, such as those shown in Fig. As shown in Figure 6, the drive shaft 142 passes through the driven rotor 152 or at least coaxially with it. Nevertheless, one or more bearings or bearing assemblies can be arranged radially between the drive shaft 142 and the driven rotor 152, so that the rotation of the drive shaft 142 is not directly transmitted to the driven rotor 152.

[0024] In general, the driven rotor 152 comprises a support substrate 154 (for example, a disk substrate) and one or more magnetic elements 156 (for example, permanent magnets). The magnetic elements 156 can, for example, be fixed to the support substrate 154 to rotate with it. In some embodiments, the one or more magnetic elements 156 comprise a plurality of circumferentially spaced (for example, uniformly spaced in the axial direction A) magnetic elements 156. As shown, the magnetic elements 156 can be embedded in the support substrate 154. The magnetic elements 156 can be arranged such that the magnetic poles facing the drive plate 144 alternate. Furthermore, the one or more magnetic elements 156 can be magnetically engaged with the drive plate 144.Conversely, the rotation of the drive plate 144 can generate an eddy current at one or more magnetic elements 156 of the driven rotor 152 (as would be understandable, for example). The driven rotor 152 can be mounted to rotate about the axial direction A or extend radially outwards from it. The rotation of the drive plate 144 can, in turn, cause the driven rotor 152 to rotate separately (for example, about the axial direction A).

[0025] In some embodiments, a cam plate 158 is attached to the support substrate 154. In particular, the cam plate 158 can be rotatably fixed to the support substrate 154 so that it rotates with it. Additionally or alternatively, the cam plate 158 can be arranged axially such that the drive plate 144 or the one or more magnetic elements 156 are positioned between the cam plate 158 and the system motor 120. In certain embodiments, the cam plate 158 defines a cam groove 160. As shown, the cam groove 160 can be defined about the central axis of the driven rotor 152 (for example, the axial direction A). For example, the cam groove 160 can be located on a bottom or

[0026] As shown, the cam plate 158 can be formed or arranged on a bottom surface or a surface of the driven rotor 152 opposite the motor (for example, opposite one or more magnetic elements 156). The cam plate 158 can, in turn, be directed away from the system motor 120. The groove 160 can have an eccentric orientation or shape relative to the central axis. Thus, a circumferentially static element (for example, a groove projection 166) that engages with or is received in the groove 160 can be moved back and forth along a radial direction between an inner position (for example, proximal to the central axis) and an outer position (for example, distal to the central axis).

[0027] In general, a lubricant pump 134 can be connected to the cam plate 158 (for example, to drive the pumping of the lubricant fluid). In some embodiments, a positive displacement pump 134 is provided. In particular, the positive displacement pump 134 can be mechanically connected to the cam plate 158 to drive the pumping of a fluid based on the rotation of the cam plate 158. In the embodiments shown, the positive displacement pump 134 comprises a linear pump or is provided as such and in turn comprises a linear piston 162 and a pump cylinder 164 in which the linear piston 162 is slidably mounted. As shown, the pump cylinder 164 defines a lubricant outlet 168 (for example, upstream of the lubricant outlet 140) and is mounted on a pump bracket 128, which is generally located within the housing 104 of the tool 100 ( Fig. 1) is static. Furthermore, the pump cylinder 164 is connected to a lubricant reservoir 130. Optionally, the lubricant reservoir 130 can be mounted above the pump cylinder 164 (for example, on the pump bracket 128).

[0028] The linear piston 162 can engage with the cam plate 158, such that the rotation of the cam plate 158 causes a linear or reciprocating motion of the piston relative to the pump cylinder 164. Thus, the linear piston 162 can be driven to pump fluid to and from the cylinder based on the movement of the cam plate 158. In exemplary embodiments, a groove projection 166 is fixed to the linear piston 162 or extends axially from it (for example, perpendicular or not parallel to the linear axis of the piston movement or to the pump cylinder 164 in general) outside the pump cylinder 164. As shown, the groove projection 166 can be accommodated in the cam groove 160.When the cam plate 158 rotates, the groove projection 166 (and thus the linear piston 162) can be moved back and forth along a radial direction between an inner position (for example, proximal to the central axis) and an outer position (for example, distal to the central axis).

[0029] Fig. Figure 7 shows a schematic representation of the operation of the lubrication system 102. The pump 134 can be operated, for example, controlled and actuated, by the motor assembly 110. The tool 100 has a control assembly 112, which includes one or more inputs 170, such as buttons or dials, to control the operation of the tool 100, including, but not limited to, the trigger 118. The control assembly 112 includes a control unit 174, for example, a printed circuit board (PCB) or other hardware and firmware, which can receive an input from the input(s) 170. The control unit 174 is functionally coupled to the motor assembly 110 to control the positive displacement pump 134 simultaneously with the motor assembly 110. The motor assembly 110 can be electrically driven by the control unit 174 to cause rotation.Therefore, if the motor assembly 110 is driven by the control unit 174, the system pump 134 (for example by the driven rotor 152) will be driven. Fig. 6) actuated to pump lubricant 132 from the lubricant reservoir 130 to the lubricant outlet 140, thereby supplying lubricant 132 to the sword and chain assembly 106.

[0030] In some embodiments, a rotation sensor 174 is provided, which communicates operationally (e.g., electrically or wirelessly) with the control unit 174. The rotation sensor 174 can generally be configured to detect an operating state of the lubrication system 102 (e.g., on / off or otherwise deactivated, switched off) or a flow rate of the lubricant 132 through the pump 134. For example, the rotation sensor 174 can be configured to detect the eddy current generated at the driven rotor 152. The control unit, in turn, can be configured to determine an operating state based on the detected eddy current. A certain absence of rotation can indicate that the lubrication system 102 is blocked. A certain rotation (e.g., rotational speed) within a predefined range can indicate proper operation of the lubrication system 102.A certain rotation above the predefined range may indicate insufficient lubricant (for example, insufficient lubricant in the lubricant reservoir 130).

[0031] Further aspects of the disclosure are indicated by one or more of the following embodiments: A lubrication system for a power tool comprises: a motor assembly; a drive plate mechanically coupled to the motor assembly to rotate with it; a driven rotor spaced apart from the drive plate, the driven rotor comprising a support substrate and one or more magnetic elements fixed to the support substrate to rotate with it, the one or more magnetic elements magnetically engaging with the drive plate to generate an eddy current with it; a cam plate attached to the support substrate to rotate with it; and a positive displacement pump mechanically connected to the cam plate to drive the pumping of a lubricating fluid based on the rotation of the cam plate.

[0032] The lubrication system of one or more of the embodiments, wherein the positive displacement pump comprises a linear piston and a pump cylinder in which the linear piston is slidably received, and the linear piston engages with the cam plate to drive a linear movement of the linear piston relative to the pump cylinder.

[0033] The lubrication system of one or more of the embodiments, in which the cam plate defines a cam groove around a central axis of the driven rotor.

[0034] The lubrication system of one or more of the embodiments, wherein the positive displacement pump comprises a linear piston and a groove projection received in the cam groove.

[0035] The lubrication system of one or more of the embodiments, in which the cam groove is defined on a bottom side of the driven rotor opposite the one or more magnetic elements.

[0036] The lubrication system of one or more of the embodiments, in which the driven rotor is axially spaced from the drive plate.

[0037] The lubrication system of one or more of the embodiments, wherein the motor assembly comprises a drive shaft to which the drive plate is fixed, and the drive shaft is coaxial to the driven rotor and rotatably decoupled from it.

[0038] The lubrication system of one or more of the embodiments, which also includes a motor fan rotatably coupled to the motor assembly and the drive plate in order to rotate with them.

[0039] The lubrication system of one or more of the embodiments, wherein the one or more magnetic elements comprise a plurality of circumferentially spaced magnetic elements embedded in the support substrate.

[0040] The lubrication system of one or more of the embodiments further comprising a rotation sensor configured to detect the eddy current, and a control unit configured to determine an operating state based on the detected eddy current.

[0041] Tool comprising: a motor assembly; a tool unit driven by the motor assembly, the tool unit comprising a guide bar and a chain circumscribing a section of the guide bar;and a lubrication system that supplies lubricant to the chain, the lubrication system comprising: a drive plate mechanically coupled to the motor assembly to rotate with it, a driven rotor spaced apart from the drive plate, the driven rotor comprising a support substrate and one or more magnetic elements fixed to the support substrate to rotate with it, the one or more magnetic elements magnetically engaging with the drive plate to generate an eddy current with it, a cam plate attached to the support substrate to rotate with it, and a positive displacement pump mechanically connected to the cam plate to drive the pumping of a lubricating fluid to the chain based on the rotation of the cam plate.

[0042] The tool of one or more of the embodiments, wherein the positive displacement pump comprises a linear piston and a pump cylinder in which the linear piston is slidably received, and the linear piston engages with the cam plate to drive a linear movement of the linear piston relative to the pump cylinder.

[0043] The tool of one or more embodiments, in which the cam plate defines a cam groove around a central axis of the driven rotor.

[0044] The tool of one or more of the embodiments, wherein the positive displacement pump comprises a linear piston and a groove received in the cam groove.

[0045] The tool of one or more of the embodiments in which the cam groove is defined on a bottom side of the driven rotor opposite the one or more magnetic elements.

[0046] The tool of one or more of the embodiments in which the driven rotor is axially spaced from the drive plate.

[0047] The tool of one or more of the embodiments, wherein the motor assembly comprises a drive shaft to which the drive plate is fixed, and the drive shaft is coaxial to the driven rotor and is rotatably decoupled from it.

[0048] The tool of one or more of the embodiments, further comprising a motor fan rotatably coupled to the motor assembly and the drive plate in order to rotate with them.

[0049] The tool of one or more embodiments, wherein the one or more magnetic elements comprise a plurality of circumferentially spaced magnetic elements embedded in the support substrate.

[0050] The tool of one or more of the embodiments further comprising a rotation sensor configured to detect the eddy current, and a control unit configured to determine an operating state based on the detected eddy current.

[0051] This written description uses examples to disclose the present application, which comprises the best embodiment, and to enable any person skilled in the art to put the disclosure into practice by manufacturing and using both devices and systems, as well as carrying out the methods contained therein. The patentable scope of the disclosure is defined by the claims and may include further examples that might occur to those skilled in the art in this field. Such further examples shall fall within the scope of the claims if they comprise structural elements that do not differ from the wording of the claims, or if they comprise equivalent structural elements that differ only insignificantly from the wording of the claims.

Claims

[1] Lubrication system for a power tool, comprising: an engine assembly; a drive plate that is mechanically coupled to the motor assembly in order to rotate with it; a driven rotor spaced apart from the drive plate, wherein the driven rotor comprises a support substrate and one or more magnetic elements fixed to the support substrate to rotate with it, wherein the one or more magnetic elements are magnetically engaged with the drive plate to generate an eddy current with it; a cam plate attached to the support substrate to rotate with it; and a positive displacement pump that is in mechanical connection with the cam plate to drive the pumping of a lubricating fluid based on the rotation of the cam plate. [2] Lubrication system according to claim 1, wherein the positive displacement pump comprises a linear piston and a pump cylinder in which the linear piston is slidably received and the linear piston engages with the cam plate to drive a linear movement of the linear piston relative to the pump cylinder. [3] Lubrication system according to claim 1, wherein the cam plate defines a cam groove around a central axis of the driven rotor. [4] Lubrication system according to claim 3, wherein the positive displacement pump comprises a linear piston and a groove received in the groove groove. [5] Lubrication system according to claim 3, wherein the cam groove is defined on a bottom side of the driven rotor opposite the one or more magnetic elements. [6] Lubrication system according to claim 1, wherein the driven rotor is axially spaced from the drive plate. [7] Lubrication system according to claim 1, wherein the motor assembly comprises a drive shaft to which the drive plate is fixed, and the drive shaft is coaxial to the driven rotor and is rotatably decoupled from it. [8] Lubrication system according to claim 1, further comprising a motor fan which is rotatably coupled to the motor assembly and the drive plate in order to rotate with them. [9] Lubrication system according to claim 1, wherein the one or more magnetic elements comprise a plurality of circumferentially spaced magnetic elements embedded in the carrier substrate. [10] Lubrication system according to claim 1, further comprising a rotation sensor configured to detect the eddy current, and a control unit configured to determine an operating state on the basis of the detected eddy current. [11] Tool, comprising: an engine assembly; a tool unit driven by the motor assembly, wherein the tool unit comprises a guide bar and a chain surrounding a section of the guide bar; and a lubrication system that supplies the chain with lubricant, wherein the lubrication system comprises: a drive plate that is mechanically coupled to the motor assembly in order to rotate with it, a driven rotor spaced apart from the drive plate, wherein the driven rotor comprises a support substrate and one or more magnetic elements fixed to the support substrate in order to rotate with it, wherein the one or more magnetic elements are magnetically engaged with the drive plate in order to generate an eddy current with it, a cam plate that is attached to the carrier substrate in order to rotate with it, and a positive displacement pump which is in mechanical connection with the cam plate to drive the pumping of a lubricating fluid to the chain based on the rotation of the cam plate. [12] Tool according to claim 11, wherein the positive displacement pump comprises a linear piston and a pump cylinder in which the linear piston is slidably received and the linear piston engages with the cam plate to drive a linear movement of the linear piston relative to the pump cylinder. [13] Tool according to claim 11, wherein the cam plate defines a cam groove around a central axis of the driven rotor. [14] Tool according to claim 13, wherein the positive displacement pump comprises a linear piston and a groove received in the groove groove. [15] Tool according to claim 13, wherein the cam groove is defined on a bottom side of the driven rotor opposite the one or more magnetic elements. [16] Tool according to claim 11, wherein the driven rotor is axially spaced from the drive plate. [17] Tool according to claim 11, wherein the motor assembly comprises a drive shaft to which the drive plate is fixed, the drive shaft being coaxial to the driven rotor and being rotatably decoupled from it. [18] Tool according to claim 11, further comprising a motor fan which is rotatably coupled to the motor assembly and the drive plate in order to rotate with them. [19] Tool according to claim 11, wherein the one or more magnetic elements comprise a plurality of circumferentially spaced magnetic elements embedded in the support substrate. [20] Tool according to claim 11, further comprising a rotation sensor configured to detect the eddy current and a control unit configured to determine an operating state based on the detected eddy current.

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